In material handling or processing systems it is often necessary to provide a device such as a hopper, shredder, conveyor, or the like which receives the material for storage or processing and eventually transfers it, either in the same or a modified form, to additional apparatus. During the process of depositing the material in the device small light particles of the material become readily easily separated from large heavies particles and may be skimmed off in a stream of air which passes through the device at relatively high velocity. Such skim classification is fully described in copending U.S. application Ser. No. 604,576, filed Aug. 14, 1975, now abandoned and assigned to the same assignee as the present application.
It has been found, however, that light particles of the material often become embedded within agglomerations or clumps of material due to the fact that the material contains substantial amounts of moisture, causing components of the material to adhere together in agglomerations or masses containing both light and heavy materials.
It has also been found that sometimes the air stream being used for the skim classification contains undesirable amounts of moisture which may be added to the materials in the device, creating undesirable problems such as odor, cohesion of particles of materials to one another, or difficulty in removing materials from the device.